Distributor issues

32truck

32truck

Junior Member
Sorry about this long winded post.
Can't get my flathead to run right. 8ba. the points in my Mallory ZC dual point distributor were pretty fried. After learning that the points were no longer available for this distributor, I Got some Napa CS756 replacements and I just can't get it to run right. I set the dwell at 26 like it says on the distributor. It appears to me like there is a lot of slop in the shaft as I was trying to set the point gap and the lobes look kinda worn to me. It idles but seems to speed up then slow down, then frequently stalls but every time I attempt to give it some gas, it runs really rough and misses no matter what I do with the timing. I'm really thinking I need a new distributor. I'm brand new to the flathead world and just got this 32 Ford pickup a few weeks ago. Any suggestions would be awesome. Thanks.

Andy
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The lobes on your distributor is worn you will have hard time setting and keeping them set. May be time for a good distributor shop to look at it or replace it. The roll [Speed up and slow down]of the engine could be the blower most blower engine's have a roll that is the cool thing about a blower motor. Nice looking engine.
 
There are multiple things to check. If you can move the distributor shaft back and forth at all, then it is worn (or the bushings) and that will influence point gap, timing, point float, etc.. If the bushings are worn out, then they need to be replaced. Looks like there could be rust on the cam - is it worn and dirty? Do you have a good dwell meter to set the point dwell and see if there is a lot of fluctuation (needle moving around) as you crank the engine over? When you see a lot of needle flutter, that is another sign of worn parts.

Also, I noticed that on the Malory Condenser (big brass sucker), that I can see what looks like a crack in the upper edge of it. Usually, this means it has failed and you need to replace it. You can PM 'TubMan' here on the Barn - he makes a custom replacement that looks the part, but has a good internal condenser that works well.
 
Bored&Stroked said:
There are multiple things to check. If you can move the distributor shaft back and forth at all, then it is worn (or the bushings) and that will influence point gap, timing, point float, etc.. If the bushings are worn out, then they need to be replaced. Looks like there could be rust on the cam - is it worn and dirty? Do you have a good dwell meter to set the point dwell and see if there is a lot of fluctuation (needle moving around) as you crank the engine over? When you see a lot of needle flutter, that is another sign of worn parts.

Also, I noticed that on the Malory Condenser (big brass sucker), that I can see what looks like a crack in the upper edge of it. Usually, this means it has failed and you need to replace it. You can PM 'TubMan' here on the Barn - he makes a custom replacement that looks the part, but has a good internal condenser that works well.
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It's hard to get a great look at the lobes, but after looking more closely, they appear to be ok. As far as the back and forth action of the shaft, yeah there is a ton of movement. I was having trouble keeping the points on the peak of the lobe to set the gap because the shaft would spin one way or the other, so there is a lot of slop. I will check the dwell needle while I crank it and see what it does. As far as the brass condenser goes, I see that line you noticed but it's not a crack. It appears to be ok. Thanks!!!

Andy

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To be perfectly clear : each set of points is set to 26 degrees dwell, not the total dwell which will end up being more. Use a little piece of cardboard to alternately block each set of points open while you set the other.

While the original Mallory brass condensers are usually quite robust, you should really test it as it is probably over 50 years old.
 
How do you know the condenser is good? Most of these old/original Mallory condensers are shot. Unless you have a high-quality condenser tester (most folks don't have one), you'll not really be able to test it. I'd get a replacement and add that to your "test and tune" kit.
 
Bored&Stroked said:
How do you know the condenser is good? Most of these old/original Mallory condensers are shot. Unless you have a high-quality condenser tester (most folks don't have one), you'll not really be able to test it. I'd get a replacement and add that to your "test and tune" kit.
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I dont know. I only said its not cracked. lol. Great point though, i get your meaning. It could be shot as far as I know. Im just trying to get ideas of what to check/replace.
 
Your Mallory has had a rough life, any more than .003 side to side movement of the rotor
shaft will be problematic. There are web sites that provide step by step tear down
and rebuild info. Some vintage Mallory's had bearings vs bushings, if yours has bearings

the fix could be easy.Could be tear down time.
Charlie ny
 
Charlie ny said:
Your Mallory has had a rough life, any more than .003 side to side movement of the rotor
shaft will be problematic. There are web sites that provide step by step tear down
and rebuild info. Some vintage Mallory's had bearings vs bushings, if yours has bearings

the fix could be easy.Could be tear down time.
Charlie ny
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Ok thanks Charlie, I'll do some looking around. Appreciate the info.

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I think there is some confusion here on your part regarding SLOP in the dist shaft and cam. Rotational free play can be a normal thing and vertical up or down movement a small amount is OK. What is critical is sideways movement which effects the point opening and cam angle and can vary the spark timing. This kind of wear is caused by worn bronze bushes that the shaft rotates in and also the shaft itself could be worn. So SIDEWAYS LEFT to RIGHT movement is what you are testing. No more than about .002" is OK. Check the ohms primary and secondary on your coil and also the current in amps draw of the coil primary with the engine at idle speed. Should be only about 3 amps. Regards, Kevin.
 
Also, there are folks that can rebuild you distributor, run it up on a machine and ensure everything is exactly as it should be.

You should ask 'Charlie ny' whether or not he works on these units - if he does, then I'd have him do the work. Unless you have a distributor machine, you really don't know how it is working (or not) . . . is sort of mandatory to correctly setup and tune these points units (in my mind).
 
Bored&Stroked said:
Also, there are folks that can rebuild you distributor, run it up on a machine and ensure everything is exactly as it should be.

You should ask 'Charlie ny' whether or not he works on these units - if he does, then I'd have him do the work. Unless you have a distributor machine, you really don't know how it is working (or not) . . . is sort of mandatory to correctly setup and tune these points units (in my mind).
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Yes I agree. I've already got Charlie's number. My 50 year old dwell meter completely quit working last night so now I'm wondering how accurate it was in the first place. Thanks to tubman, I now know how to set the dwell for each set though! Lol. Well if anybody has a suggestion for a decent new dwell meter, I'd like to give it one more shot before sending it to somebody who knows what they are doing. I hate to give up this easily, but the frustration is getting the better of me[emoji1787]

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Also, my "slop" in the shaft is rotational, not side to side or up and down. My thinking on this, was that the mechanical advance had weak springs or something similar and was messing with the timing prematurely. I'm probably wrong on this.

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My $.02 worth
Lose the duel point Mallory (hang it on the wall as a conversation piece). More trouble than it worth [kool factor]. To maintain and tune that Mallory you are going to need access to a distributor machine.
Sure, it can be done "old school" but we also spent every night in the shop futzing or bench racing (brainstorming) with our buddies. Not many of us left anymore.

Get a chebby type distributor with a magnetic pickup to drive a [digital] MSD electronic control box. Very tunable especially with a blower and pretty bulletproof. You are going to have enough problems maintaining the fuel system without compounding that problem with ignition headaches.
Besides, you have already lost the "nostalgia look" with the electric fan, yellow ACCEL fruit jar coil and chrome alternator. The MSD can be installed under the dash and you get to use a "retro" style 12 volt coil or continue using the quart fruit jar ACCEL coil
 
I use MSD stuff on a lot of my cars (mostly in the race world). One thing that is super good about some of the units is that the timing can be linked to BOOST. Essentially you can program the timing curve to take out some timing as the boost comes up. This is especially valuable to control detonation.

Some of the boost retard mechanisms are mechanical (you turn a knob) - others are completely driven by boost sensors and computer CPUS. For a boosted street car, I especially like the ability to tune the advance curve with my laptop - as I can deal with various fuel conditions (rich/lean), altitudes, bad gas, etc..
 
Does it have mechanical weights and springs to advance the timing? I see in one of your pictures there's a plug, looks like a vacuum connection.
 
Set both set of points to exactly .018 !!
Odds are condensor is fine they all crack we have ran them for years put some nail polish on the cracks .
Measure the resistance of that accel coil you need approx 1.5 ohms ..ay need to madd resistor in the feed line .............
Should run just fine if not work with the timing , and air fuel with that blower

You can adjust advance by bending tab seen thru adjustment hole .......
 
solidaxle said:
Did a little poking around HAMB. The ZC distributors use both centrifugal and vacuum to advance the timing.
https://www.jalopyjournal.com/forum/threads/mallory-zc-flat-top-distributor-w-vac-advance.1174173/


I'm not seeing a vacuum line on your set up.
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Thanks so much. Yeah I wondered if that was vacuum that was plugged off but I'm really unfamiliar with it. I spoke with CharlieNY and sent it to him to check into it. He just recently worked on one and found issues with the plunged inside there.

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